Changes in cell culture temperature alter release of inflammatory mediators in murine macrophagic RAW264.7 cells

Objectives: To examine whether moderate changes in cell culture temperature influence the production of various cytokines and associated mediators of inflammation. Methods: We performed lipopolysaccharide (LPS) stimulation of the murine macrophagic RAW264.7 cell line under hyperthermic (40 °C), normothermic (37 °C) and hypothermic (34 °C) conditions. We then measured the levels of heat shock protein 70 (HSP70), heat shock factor protein (HSF) and nuclear factor–kB (NF-kB) dimers (p50 and p65) in the cells, and the levels of high mobility group box 1 (HMGB1) and the cytokines tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β) and interleukin 6 (IL-6) in the culture supernatants. Results: Levels of HMGB1, IL-1β, IL-6, and TNF-α, as well as NF-kB dimers (p50 and p65), were all reduced following LPS stimulation at 40 °C and 34 °C compared with those at 37 °C. Levels of HSP70 and HSF increased at 40 °C and 34 °C. Conclusions: The application of moderate hyperthermia and hypothermia after LPS-induced cell activation attenuated the inflammatory response and reduced the likelihood of cell damage. These findings suggest that moderate temperature changes modulate the inflammatory response and could be a useful therapy against sepsis. Received 1 October 2006; returned for revision 16 November 2006; returned for final revision 23 January 2007; accepted by M. Katori 14 March 2007